Sound Absorption and Transmission of Flat, Tensioned Membranes

Abstract

Membrane cushions are often used by architects to create ceilings of gathering spaces such as shopping centra and atria but also sport stadiums, playgrounds or archaeological and historical ruins covering. The acoustic atmosphere in these spaces is important for speech intelligibility and pleasantness, and is closely related to background noise and room acoustic parameters. It is known from literature and previous research conducted by the authors that the ETFE membranes exhibit a certain acoustic transparency[1]. Considering the placement of ETFE membranes and cushions, this transparency can be considered as absorption from a room acoustic point of view. This is what is referred to as “effective absorption” by the authors. The precise dynamics of a typical ETFE membrane are, however, not described in literature. Therefore, in this paper, numerical calculations are described that indicate how a smaller membrane behaves. The finite size and the tension of the membrane is taken into account, as well as the mutual vibro-acoustic coupling between the membrane and the surrounding medium. Because of computer resource requirements, the simulations are limited to the lower frequency range.